Groups Shifting

I have recently built a custom 6MM Remington Rifle with a tight neck chamber,.271, mounted with a 8-32x Nightforce scope using Kelby rings and Davidson bases. I am using 70 gr.Sierra BlitzKing bullets with 50 grains of H4350 powder traveling at 3720 fps. I lapped the rings. I am not certain for sure there is a problem yet, but the rifle was sighted in at 250 yards and as I moved the target out to further yardages, 300, 350, 400 the groups seemed to shift to the left there was some wind and gusts when I did this. I want to confirm this but could it be anything else besides the wind?

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"I also thought that you might be in Australia with that Flemington location and was going to offer Coriolis but NJ is in the incorrect hemisphere for left shift I believe."<HR></BLOCKQUOTE>

I hate to correct you, but... New Jersey shifted to the left many years ago, and hasn't got it straight yet [img]images/icons/wink.gif[/img] [img]images/icons/wink.gif[/img]

i had a benchrest shooter tell me this one time.he said he and a friend set up targets from 100 to 600 yards so that when you fired one shot it went through every target.what you find will blow you away.he told me because i said my 22-250 shot center at 100 but to the left at 200 back to center at 300 but shot smaller groups at 300.he said bullets yaw and change there poi from one range to the next not just there vertical.sound like bs i know but try it sometimes,thanks,keith

Its a Hart heavy bull 26.5 inch barrel, 1 and 12 twist I believe the twist goes counterclockwise. I did use an anticant device when I mounted the scope. Can't remember the name, but it is u-shaped with a bubble on top and you view a vertical string at say 100 yards. The vertical cross hair has to line up with the string.